Marin Municipal Water District responds to grand jury report endorsing herbicide use to reduce fire risk on Mount Tamalpais

Whether the Marin Municipal Water District will use herbicides in the future to control the spread of French broom in the Mount Tamalpais watershed has yet to be seen, but the district has issued a response to the Marin County Civil Grand Jury's report that urged the district to do so in the name of reducing fire risk.

The district's response to the March report was approved Tuesday by its Board of Directors and is ambivalent about the herbicide use issue. District members said they are not making any decisions until after an environmental impact report on vegetation management options is complete. The draft environmental impact report is slated for publication in December.

Director Jack Gibson said the grand jury's report comes at a tricky time.

"To presume we're going one way or another is premature," Russell said.

The environmental impact report will explore two options. One option is simply continuing to manually remove broom at the cost of $5.6 million a year; the other would combine the manual efforts with the controlled use of herbicides at a cost of $1.6 million a year.

The watershed supplies drinking water to much of Marin with the exception of Novato and parts of West Marin. It consists of 18,900 acres and borders 11 communities: Mill Valley, San Anselmo, Ross, Kentfield, Fairfax, Larkspur, Corte Madera, Woodacre, Lagunitas, Forest Knolls and San Geronimo. Those communities account for 13,200 structures within one mile of the watershed boundary.

One big issue of contention in the community is whether glyphosate, the active ingredient in Roundup, is safe to use in a watershed. The water district used glyphosate for three years until August 2005, when the Board of Directors imposed a moratorium on the use of herbicides after residents voiced concerns about potential health impacts if the chemical leached into reservoirs.

During public comment, William Binzen said glyphosate use is unacceptable. He advocated for expanding existing fire breaks and conducting more prescribed burns.

"Glyphosate is the most dangerous compound generally found in our environment. The day glyphosate appears in the water we drink, it will start making people sick — poisoned from the micro-flora of their gut outward," Binzen said.

Though most of the district's response to the grand jury report was ambivalent, the district partially disagreed with the grand jury's recent conclusion that current scientific studies indicate the use of glyphosate with an approved surfactant — a material that reduces the surface tension of water — poses no significant risks.

In its response, the district said a 2010 assessment "identified some potential risks associated with the use of glyphosate, but found that risks can be minimized by taking appropriate safeguards." It said an updated risk assessment will be incorporated into the pending environmental impact report on the two vegetation management options.

In response to the grand jury's recommendation that the board act on policies that are the most effective in controlling broom and wildfire, the district said it will "act on policies that first safeguard the quality of drinking of water derived from watershed lands, protect watershed visitors and ensure the ecological integrity of the lands."

While the district agreed with the grand jury that there has been a 300-acre increase of broom in the watershed since 2006, it contested the statement that this is a result of the district's decision not to use herbicides and that this decision subsequently led to a higher risk of wildfires.

"Although having so much broom in the system increases the level of effort needed to implement our vegetation management goals, we continue to mow and pull broom to maintain fuel break effectiveness on an annual basis," the district said in its response.

Board member Liza Crosse said she doesn't appreciate the grand jury's implication that the district's decision to cease using herbicides has caused more broom to grow.

"I don't like the idea that the language attributes to the district that somehow we've made broom happen," Crosse said. "It's a mischaracterization."